This invention relates to a fluid injection system for injecting additives into a fluid flowing through a pipeline. In particular, this invention relates to an apparatus for accurately calibrating the injection pump used in the fluid injection system.
Injection pumps are used in a variety of applications for injecting additives into pipelines. One industry that extensively uses injection pumps is the gas transmission industry. Transporting pure natural gas is extremely dangerous because the gas is invisible and odorless. Thus, gas leaks are not readily detected by humans. To provide for prompt and effective gas leak detection, odorants are injected into the gas pipelines. Some additional uses for injection pumps include, injecting chlorine into water lines; injecting corrosion and scale inhibitors into petrochemical lines; and injecting coloring agents into food processing lines.
One type of injection pump used for these and other applications is made by Williams Instrument Company, Inc. of Valencia, Calif. 91355. This pump is commonly known by its registered trade name, OSCILLAMATIC. Injection pumps, like the Williams Instrument OSCILLAMATIC pump, generally incorporate a means for regulating the amount of additive injected into the pipeline. The regulation means might comprise an adjustable restriction device that limits the movement of the pumping mechanism. In the case of the Williams Instrument OSCILLAMATIC pump, the pumping mechanism is a plunger connected to a piston. By adjustably restricting the movement of the piston, the stroke length of the plunger is controlled. Adjusting the stroke length of the plunger causes the injection of more or less additive, as desired, into the pipeline. In the Williams Instrument OSCILLAMATIC pump, the adjustable restriction device is a threaded stud screwed into the top of the pump that contacts the top of the piston. By screwing the stud in, the movement of the piston is additionally restricted reducing the stroke length of the pumping plunger, thereby decreasing the amount of fluid injected into the pipeline for each stroke of the pumping plunger. Similarly, screwing the stud out results in an increased plunger stroke length and the injection of more fluid into the pipeline for each stroke of the pumping plunger.
However, heretofore, there was no simple device for accurately calibrating the regulation means to control the precise amount of additive injected into the pipeline. Yet, precision in controlling the amount of additive injected into the pipeline is generally desireable and frequently necessary.